JP2016204481A - Acid modified polyolefin resin aqueous dispersion and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aqueous dispersion of an acid modified polyolefin resin having good dispersion stability without containing a nonvolatile aqueous dispersion auxiliary or a basic compound and excellent in adhesion and water resistance.SOLUTION: There is provided an acid modified polyolefin resin aqueous dispersion obtained by dissolving an acid modified polyolefin resin in a specific organic solvent, adding it to an aqueous medium and then volatilizing the organic solvent, and containing practically no nonvolatile aqueous dispersion auxiliary or no basic compound. There is provided an acid modified polyolefin resin aqueous dispersion having the content of unsaturated carboxylic acid of the acid modified polyolefin resin of 0.01 to 1 mass% and pH of 4.0 to 11.0.SELECTED DRAWING: None

Description

  The present invention relates to an acid-modified polyolefin resin aqueous dispersion.

  Polyolefin resins represented by polyethylene and polypropylene have various excellent properties such as mechanical properties, transparency, electrical properties, surface gloss, chemical resistance, water resistance, and solvent resistance. It is used in large quantities in a wide range of applications, such as packaging and daily goods. As a method for using such a polyolefin resin, a method is known in which a polyolefin resin is processed into an aqueous dispersion to form a coating agent.

  Some aqueous dispersions of polyolefin resins do not contain non-volatile aqueous dispersion aids such as emulsifiers, and are characterized by excellent adhesion and water resistance. For the production of aqueous dispersions of polyolefin resins, an acid-modified polyolefin resin in which an acid component such as an unsaturated carboxylic acid is introduced into the polyolefin resin is used as a raw material. The higher the acid component content, the easier the aqueous dispersion becomes. Tend. On the other hand, in Patent Document 1, an aqueous polyolefin resin solution obtained by a production method called a self-emulsification method without using a non-volatile aqueous dispersion aid, although the content of unsaturated carboxylic acid is small. Dispersions are described. Since this aqueous dispersion does not contain a so-called emulsifier or has a low content of unsaturated carboxylic acid, it is excellent in various performances such as adhesion and water resistance. ing.

  An aqueous dispersion of a polyolefin resin having no emulsifier as described above is obtained by neutralizing an acid component such as a carboxylic acid contained in a resin skeleton with a basic compound such as ammonia, an amine, or an alkali metal salt. The dispersion stability of the resin particles in the solvent is maintained, and the basic compound as described above is essential from the viewpoint of dispersion stability during production and storage.

  On the other hand, as an aqueous resin dispersion method, a so-called phase inversion emulsification method is known in which an organic solvent solution of a resin is mixed and dispersed in water together with a non-volatile aqueous dispersion aid such as an emulsifier (for example, patents). Reference 2). However, even such a phase inversion emulsification method requires the use of either a non-volatile aqueous dispersion aid or a basic compound as a neutralizing agent, or both.

  Therefore, the conventional aqueous dispersion of polyolefin resin that does not contain non-volatile aqueous dispersion aids, since the basic compound as a neutralizing agent is an essential component, the pH of the liquid inevitably becomes alkaline, and the liquidity is reduced. When neutral or acidic, there was a problem in dispersion stability (acid-modified polyolefin resin particles could not be uniformly dispersed in an aqueous medium, and aggregation or precipitation occurred). In addition, the basic compound has problems in odor and safety, and it is necessary to consider the production environment and use environment of the aqueous dispersion.

  As described above, no acid-modified polyolefin resin aqueous dispersion substantially free of a non-volatile aqueous dispersion aid has ever existed that does not substantially contain a basic compound.

  Even in Patent Document 1, there is no specific description about an aqueous dispersion method of a polyolefin resin having a very low acid modification rate such that the content of unsaturated carboxylic acid in the acid modified polyolefin resin is 1% by mass or less, Further, in other documents, there is no specific description relating to aqueous dispersion of an acid-modified polyolefin resin having an unsaturated carboxylic acid content of 1% by mass or less.

JP 2003-119328 A JP 2006-36920 A

  The present invention solves the problems as described above, and is an aqueous dispersion containing an acid-modified polyolefin resin and an aqueous medium, and substantially comprises a non-volatile aqueous dispersion aid and a basic compound. It is an object of the present invention to provide an aqueous dispersion of an acid-modified polyolefin resin that has long-term dispersion stability and is excellent in adhesion to a substrate and water resistance even if it is not contained. Further, an aqueous dispersion of acid-modified polyolefin resin having a low content such as an unsaturated carboxylic acid content of 0.01 to 1% by mass can be provided.

  As a result of intensive studies to solve the above problems, the present inventors have dissolved an acid-modified polyolefin resin in a specific organic solvent at a very dilute concentration such as 1% by mass or less, and this is dissolved in an aqueous medium. Then, the present inventors have found that the above-mentioned problems can be solved by volatilizing the organic solvent in the obtained liquid mixture, and reached the present invention.

That is, the gist of the present invention is as follows.
(1) An acid-modified polyolefin resin aqueous dispersion containing an acid-modified polyolefin resin and an aqueous medium, and substantially free of a non-volatile aqueous dispersion aid and a basic compound.
(2) The acid-modified polyolefin resin aqueous dispersion according to (1), wherein the pH is 4.0 to 11.0.
(3) The acid-modified polyolefin resin aqueous dispersion according to (1) or (2), wherein the content of the unsaturated carboxylic acid in the acid-modified polyolefin resin is 0.01 to 1% by mass.
(4) The acid-modified polyolefin resin aqueous dispersion as described in any one of (1) to (3), wherein the acid-modified polyolefin resin is an acid-modified ethylene / α-olefin copolymer.
(5) The mass ratio (ethylene / α-olefin) of ethylene and α-olefin constituting the acid-modified ethylene / α-olefin copolymer is 60/40 to 99/1 (1) ) To (4) The acid-modified polyolefin resin aqueous dispersion according to any one of the above.
(6) An acid-modified polyolefin resin solution containing an acid-modified polyolefin resin in a water-soluble organic solvent having a boiling point of 100 ° C. or less in an amount of 1% by mass or less of the total solution is 1.5 times as much as the aqueous solution. A method for producing an aqueous dispersion of an acid-modified polyolefin resin, which is added to a medium and then volatilizes at least a part of a water-soluble organic solvent having a boiling point of 100 ° C. or less in the obtained mixed solution by a solvent removal treatment .

  The aqueous dispersion of the acid-modified polyolefin resin of the present invention is excellent in dispersion stability over a long period of time despite being substantially free of both the nonvolatile aqueous dispersion aid and the basic compound. Excellent adhesion to water and water resistance. Moreover, since it does not contain a basic compound, it does not have problems caused by basic compounds such as odor and safety. Furthermore, the pH of the aqueous dispersion has dispersion stability in any region from acidic to alkaline.

Hereinafter, the present invention will be described in detail.
The aqueous dispersion of acid-modified polyolefin resin of the present invention (hereinafter sometimes referred to as “aqueous dispersion”) contains an acid-modified polyolefin resin and an aqueous medium.

<Acid-modified polyolefin resin>
First, the acid-modified polyolefin resin will be described.
Examples of the olefin component which is the main component of the acid-modified polyolefin resin include ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene and 1-nonene. , 1-decene, 1-undecene, and 1-dodecene are preferable, and a mixture thereof may be used. Among these, ethylene, propylene, and 1-butene are particularly preferable from the viewpoints of adhesion and water resistance.

  The acid-modified polyolefin resin in the present invention is a copolymer containing an olefin component and an unsaturated carboxylic acid as a copolymerization component. By containing an unsaturated carboxylic acid, processing into an aqueous dispersion becomes possible. The content of the unsaturated carboxylic acid is preferably in the range of 0.01 to 1% by mass with respect to 100% by mass of the acid-modified polyolefin resin from the viewpoint of adhesion and water resistance, and the lower limit is 0.05% by mass or more. Is more preferably 0.1% by mass or more, particularly preferably 0.2% by mass or more, more preferably 0.8% by mass or less, and further preferably 0.5% by mass or less. When the amount is less than 0.01% by mass, processing into an aqueous dispersion is difficult, and when it exceeds 1% by mass, adhesion and water resistance may be deteriorated.

Unsaturated carboxylic acids include acrylic acid, methacrylic acid, (anhydrous) maleic acid, (anhydrous) itaconic acid, (anhydrous) aconitic acid, fumaric acid, crotonic acid, citraconic acid, mesaconic acid, allyl succinic acid, etc. A compound having at least one carboxyl group or acid anhydride group in the molecule, such as a half ester or half amide of a saturated dicarboxylic acid, can be used. Of these, (anhydrous) maleic acid, acrylic acid, and methacrylic acid are preferred, and maleic anhydride is more preferred from the viewpoint of ease of introduction into the polyolefin resin. In addition, “(anhydrous) to acid” means “to acid or anhydrous to acid”. That is, (anhydrous) maleic acid means maleic acid or maleic anhydride.
The acid anhydride unit introduced into the acid-modified polyolefin resin tends to take an acid anhydride structure in a dry state, and a part or all of the acid anhydride unit tends to open in an aqueous medium described later.

  The copolymerization form of the unsaturated carboxylic acid and the olefin component is not limited, and examples thereof include random copolymerization, block copolymerization, and graft copolymerization. From the viewpoint of ease of polymerization, graft copolymerization is required. Is preferred.

  In the present invention, specific examples of the acid-modified polyolefin resin include ethylene / propylene / (anhydrous) maleic acid copolymer, ethylene / 1-butene / (anhydrous) maleic acid copolymer, ethylene / propylene / 1-butene / Ethylene / α-olefin / (anhydrous) maleic acid copolymer such as (anhydrous) maleic acid copolymer, propylene / 1-butene / (anhydrous) maleic acid copolymer, propylene / octene / (anhydrous) maleic acid copolymer Examples thereof include a polymer, an ethylene / acrylic acid ester / (anhydrous) maleic copolymer, an ethylene / (anhydrous) maleic acid copolymer, and a propylene / (anhydrous) maleic acid copolymer. These may be used singly or in combination of two or more having the structure defined in the present invention. Among these, ethylene / α-olefin / (anhydrous) maleic acid copolymer is preferable from the viewpoints of adhesion to a substrate, particularly adhesion to a polyolefin resin substrate, flexibility of a coating film, and low-temperature adhesion. Of these, ethylene / 1-butene / (anhydrous) maleic acid copolymer is more preferable.

  In the ethylene / α-olefin / (anhydrous) maleic acid copolymer, the mass ratio of ethylene to α-olefin (ethylene / α-olefin) is preferably in the range of 60/40 to 99/1, 70 / 30 to 97/3 is more preferable, and 80/20 to 95/5 is even more preferable. If the mass ratio of ethylene and α-olefin is outside this range, it may be difficult to produce a resin, or the adhesiveness of the resulting aqueous dispersion may be deteriorated.

  The copolymer of ethylene and α-olefin is preferably produced using a metallocene catalyst. The ethylene / α-olefin copolymer produced by this method has a narrow molecular weight distribution, a small amount of low molecular weight components, and uniform copolymerization.

The acid-modified polyolefin resin in the present invention may contain other components other than those described above as necessary. Other units include: (meth) acrylic acid esters such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, maleic acid such as dimethyl maleate, diethyl maleate, dibutyl maleate Acid esters, (meth) acrylic amides, alkyl vinyl ethers such as methyl vinyl ether and ethyl vinyl ether, vinyl esters such as vinyl formate, vinyl acetate, vinyl propionate, vinyl pivalate, vinyl versatate and vinyl esters Vinyl alcohol, 2-hydroxyethyl acrylate, glycidyl (meth) acrylate, (meth) acrylonitrile, styrene, substituted styrene, vinyl halides, vinylidene halides, carbon monoxide, two Sulfur and the like, may be a mixture thereof.
The content of these other units is preferably 10% by mass or less of the acid-modified polyolefin resin.

  In this invention, it is preferable that it is the range of 20-150 degreeC, and, as for melting | fusing point of acid-modified polyolefin resin, it is more preferable that it is 20-100 degreeC. When the melting point is less than 20 ° C., the adhesiveness in a high temperature environment tends to decrease, and when it exceeds 150 ° C., the film forming property tends to deteriorate.

  The weight average molecular weight of the acid-modified polyolefin resin is preferably 5,000 to 300,000, more preferably 10,000 to 250,000, still more preferably 30,000 to 200,000, and particularly preferably 40,000 to 100,000. If the weight average molecular weight of the acid-modified polyolefin resin is less than 5,000, the adhesiveness tends to decrease. On the other hand, when the weight average molecular weight exceeds 300,000, it tends to be difficult to obtain an aqueous dispersion.

  In general, a polyolefin resin is hardly soluble in a solvent, which may make it difficult to measure the molecular weight. In such a case, the melt flow rate value indicating the fluidity of the molten resin is preferably used as a measure of the molecular weight.

  It is preferable that the melt flow rate value (190 degreeC according to ISO1133, 21.2N load) of acid-modified polyolefin resin (A) is 0.01-1000 g / 10min, and is 0.05-500 g / 10min. More preferably, it is 0.1 to 300 g / 10 min, more preferably 0.5 to 100 g / 10 min. When the melt flow rate value exceeds 1000 g / 10 min, the adhesiveness tends to decrease. On the other hand, when the melt flow rate value is less than 0.01 g / 10 min, an aqueous dispersion tends to be difficult to obtain.

<Aqueous medium>
The aqueous medium in the present invention is water or a liquid containing water as a main component, and may contain an organic solvent in order to improve the wettability to the base material when the aqueous dispersion is coated. Good. Examples of the organic solvent include methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, tert-butanol, n-amyl alcohol, isoamyl alcohol, sec-amyl alcohol, tert-amyl alcohol, Alcohols such as 1-ethyl-1-propanol, 2-methyl-1-butanol, n-hexanol and cyclohexanol, ketones such as methyl ethyl ketone, methyl isobutyl ketone, ethyl butyl ketone and cyclohexanone, ethers such as tetrahydrofuran and dioxane , Ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, sec-butyl acetate, 3-methoxybutyl acetate, methyl propionate, Esters such as ethyl onate, diethyl carbonate, dimethyl carbonate, glycol derivatives such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol ethyl ether acetate, -Methoxy-2-propanol, 1-ethoxy-2-propanol, 3-methoxy-3-methyl-1-butanol, methoxybutanol, acetonitrile, dimethylformamide, dimethylacetamide, diacetone alcohol, ethyl acetoacetate, 1,2- Examples include dimethyl glycerin, 1,3-dimethyl glycerin, and trimethyl glycerin.
Among these, ethanol, n-propanol, isopropanol, n-butanol, methyl ethyl ketone, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, and diethylene glycol monomethyl ether are preferable from the viewpoint of improving paintability, and ethanol, n- Propanol and isopropanol are more preferred. In the present invention, a mixture of these organic solvents may be used. The content of the organic solvent is not particularly limited, but is preferably 50% by mass or less with respect to the entire aqueous medium from the viewpoint of improving paintability.

<Aqueous dispersion>
Next, the acid-modified polyolefin resin aqueous dispersion will be described.
The aqueous dispersion of the present invention contains the acid-modified polyolefin resin and an aqueous medium, and the form thereof is one in which particles of the acid-modified polyolefin resin are uniformly dispersed in the aqueous medium. Uniform dispersion means that, in terms of appearance, a portion where the solid content concentration is locally different from other portions such as precipitation, phase separation or skinning is not found in the aqueous dispersion.

  The acid-modified polyolefin resin particles dispersed in the aqueous dispersion preferably have a volume average particle size of 0.5 μm or less. From the viewpoint of ease of coating and storage stability, 0.001 to 0.001. It is more preferably 4 μm, further preferably 0.002 to 0.2 μm, particularly preferably 0.005 to 0.15 μm, and most preferably 0.01 to 0.1 μm.

  Since the acid-modified polyolefin resin aqueous dispersion of the present invention contains substantially no basic compound, it is stable in a wide range from acidic to alkaline. Among these, the pH of the aqueous dispersion is preferably 4.0 to 11.0, more preferably 5.0 to 8.0, and even more preferably 5.0 to 7.0. If the pH is out of the range of 4.0 to 11.0, the stability may deteriorate.

  In the present invention, the content of the acid-modified polyolefin resin in the aqueous dispersion can be appropriately selected according to the coating conditions, coating thickness, performance, etc., and is not particularly limited. However, the viscosity of the aqueous dispersion is appropriately maintained. And it is preferable that it is 1-50 mass% at the point which expresses favorable coating property, It is more preferable that it is 2-30 mass%, It is more preferable that it is 3-20 mass%, 4-10 It is particularly preferable that the content is% by mass.

  The viscosity of the aqueous dispersion is not particularly limited, but the viscosity measured at 20 ° C. with a B-type viscometer is preferably 4 to 100,000 mPa · s.

  The acid-modified polyolefin resin aqueous dispersion of the present invention contains substantially no non-volatile aqueous dispersion aid. In the present invention, an acid-modified polyolefin resin can be stably dispersed in an aqueous medium in the range of a volume average particle diameter of 0.5 μm or less without using an aqueous dispersion aid. Since the aqueous dispersion in the present invention does not substantially contain a nonvolatile aqueous dispersion aid, it has excellent adhesion to the substrate, water resistance, etc., and these performances hardly change over the long term. .

  Here, the “aqueous dispersion aid” is a drug or compound added for the purpose of promoting aqueous dispersion or stabilizing the aqueous dispersion in the production of the aqueous dispersion. Means that it does not have a boiling point at normal pressure or has a high boiling point (for example, 300 ° C. or higher) at normal pressure.

  In the present invention, “substantially free of non-volatile aqueous dispersion aid” means that it is not necessary to use such aid during production (when the acid-modified polyolefin resin is dispersed in water), and the resulting aqueous dispersion Means that it does not contain this auxiliary as a result. Therefore, the content of such an aqueous dispersion aid is particularly preferably zero. However, when the aqueous dispersion aid is required for the purpose of using the aqueous dispersion, the effect of the present invention is not impaired. In the acid-modified polyolefin resin component, it may be contained by adding 5% by mass or less, preferably 2% by mass or less, more preferably less than 0.5% by mass.

  Examples of the non-volatile aqueous dispersion aid used in the present invention include an emulsifier described later, a compound having a protective colloid effect, a modified wax, a high acid value acid-modified compound, a water-soluble polymer, and the like.

  Examples of the emulsifier include a cationic emulsifier, an anionic emulsifier, a nonionic emulsifier, and an amphoteric emulsifier. In addition to those generally used for emulsion polymerization, surfactants are also included. For example, anionic emulsifiers include higher alcohol sulfates, higher alkyl sulfonates, higher carboxylates, alkyl benzene sulfonates, polyoxyethylene alkyl sulfate salts, polyoxyethylene alkyl phenyl ether sulfate salts, vinyl sulfosuccinates. Nonionic emulsifiers include polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyethylene glycol fatty acid ester, ethylene oxide propylene oxide block copolymer, polyoxyethylene fatty acid amide, ethylene oxide-propylene oxide. Compounds having a polyoxyethylene structure such as copolymers and sorbitan derivatives such as polyoxyethylene sorbitan fatty acid esters And examples of the amphoteric emulsifiers, lauryl betaine, lauryl dimethyl amine oxide, and the like.

  Compounds having protective colloid action, modified waxes, acid-modified compounds with high acid value, water-soluble polymers include polyvinyl alcohol, carboxyl group-modified polyvinyl alcohol, carboxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, modified starch, polyvinylpyrrolidone Polyacrylic acid and salts thereof, carboxyl group-containing polyethylene wax, carboxyl group-containing polypropylene wax, carboxyl group-containing polyethylene-propylene wax, and other acid-modified polyolefin waxes having a number average molecular weight of usually 5000 or less and salts thereof, acrylic acid-anhydride Maleic acid copolymer and salt thereof, styrene- (meth) acrylic acid copolymer, ethylene- (meth) acrylic acid copolymer, isobutylene-maleic anhydride A carboxyl group-containing polymer having an unsaturated carboxylic acid content of 10% by mass or more, such as an acid alternating copolymer, a (meth) acrylic acid- (meth) acrylic acid ester copolymer, and a salt thereof, polyitaconic acid and a salt thereof, amino Examples thereof include water-soluble acrylic copolymers having a group, gelatin, gum arabic, and casein, and compounds generally used as fine particle dispersion stabilizers.

  The acid-modified polyolefin resin aqueous dispersion of the present invention contains substantially no basic compound. The present invention provides a stable solution of an acid-modified polyolefin resin in an aqueous medium with a volume average particle diameter of 0.5 μm or less without using a basic compound for neutralizing the unsaturated carboxylic acid component of the acid-modified polyolefin resin. Can be dispersed. Since the aqueous dispersion in the present invention does not substantially contain a basic compound, it does not have the problems caused by the basic compound such as odor and safety. Furthermore, the aqueous dispersion obtained without substantially containing the basic compound has dispersion stability in any region from acidic to alkaline.

  Here, the “basic compound” is a compound having an action of neutralizing a carboxyl group in the acid-modified polyolefin resin, and examples thereof include ammonia, an amine, and an alkali metal salt. Specific examples of amines include triethylamine, N, N-dimethylethanolamine, isopropylamine, aminoethanol, dimethylaminoethanol, diethylaminoethanol, ethylamine, diethylamine, isobutylamine, dipropylamine, 3-ethoxypropylamine, and 3-diethylamino. Propylamine, sec-butylamine, propylamine, n-butylamine, 2-methoxyethylamine, 3-methoxypropylamine, 2,2-dimethoxyethylamine, monoethanolamine, morpholine, N-methylmorpholine, N-ethylmorpholine, pyrrole, Examples include pyridine. Specific examples of the alkali metal salt include lithium salt, potassium salt, sodium salt and the like.

  In the present invention, “substantially free of a basic compound” means that it is not necessary to use a basic compound at the time of production (at the time of aqueous dispersion of the acid-modified polyolefin resin), and the resulting aqueous dispersion is consequently obtained. It means not containing a basic compound. Accordingly, it is most preferable that the basic compound has a content of zero. However, when the basic compound is required for the purpose of use of the aqueous dispersion, the acid-modified polyolefin is within the range that does not impair the effects of the present invention. 1% by mass or less, preferably 0.5% by mass or less, more preferably 0.2% by mass or less, and particularly preferably 0.1% by mass or less with respect to 100% by mass of the aqueous resin dispersion. It does not matter.

<Additives>
In the acid-modified polyolefin resin aqueous dispersion of the present invention, in order to further improve the performance depending on the purpose, a resin other than the crosslinking agent and the acid-modified polyolefin (hereinafter sometimes referred to as “other resin”), inorganic Additives such as particles, pigments and dyes can be added.

As the crosslinking agent, a crosslinking agent having self-crosslinking property, a crosslinking agent having a plurality of functional groups that react with a carboxyl group in the molecule, a metal complex having a polyvalent coordination site, and the like can be used.
Specifically, an oxazoline crosslinking agent, an isocyanate crosslinking agent (including a block type), an amine crosslinking agent, a carbodiimide crosslinking agent, a melamine crosslinking agent, a urea crosslinking agent, an epoxy crosslinking agent, a zirconium salt compound, Examples thereof include silane coupling agents and organic peroxides.
Among these, a crosslinking agent having a plurality of functional groups that react with carboxyl groups in the molecule is more preferable. Examples of such crosslinking agents include oxazoline crosslinking agents, epoxy crosslinking agents, carbodiimide crosslinking agents, isocyanate crosslinking agents, amine crosslinking agents, and melamine crosslinking agents. Among these, an oxazoline-based crosslinking agent, an isocyanate-based crosslinking agent, an amine-based crosslinking agent, and a carbodiimide-based crosslinking agent are preferable because they are excellent in the effect of improving adhesiveness. An isocyanate-based crosslinking agent, an amine-based crosslinking agent, and an epoxy-based crosslinking agent. Is particularly preferred.
These crosslinking agents may be used in combination. The crosslinking agent may be a low molecular weight compound or a polymer type.
The addition amount of the crosslinking agent is preferably 0.1 to 30 parts by mass with respect to 100 parts by mass of the acid-modified polyolefin resin in the aqueous dispersion, from the viewpoint of sufficiently forming a crosslinked structure. It is more preferable that it is a mass part, and it is still more preferable that it is 0.5-15 mass parts.

Other resins include, for example, polyvinyl acetate, ethylene-vinyl acetate copolymer, polyvinyl chloride, polyvinylidene chloride, ethylene- (meth) acrylic acid copolymer, ethylene- (meth) acrylic acid ester-maleic anhydride. Acid copolymer, styrene-maleic acid resin, styrene-butadiene resin, butadiene resin, acrylonitrile-butadiene resin, poly (meth) acrylonitrile resin, (meth) acrylamide resin, chlorinated polyethylene resin, chlorinated polypropylene resin, polyester resin, Examples thereof include modified nylon resins, polyurethane resins, rosin-based and terpene-based tackifier resins, phenol resins, silicone resins, and epoxy resins. You may mix and use several things as needed. Among these, a polyurethane resin is preferable from the viewpoint of further improving the adhesive performance.
The addition amount of the other resin is preferably 5 to 300 parts by mass, more preferably 5 to 200 parts by mass, and more preferably 10 to 150 parts by mass with respect to 100 parts by mass of the acid-modified polyolefin resin from the viewpoint of adhesiveness. It is more preferable that it is a mass part, and it is especially preferable that it is 20-100 mass parts.

  Examples of inorganic particles include metal oxides such as magnesium oxide, zinc oxide and tin oxide, inorganic particles such as calcium carbonate and silica, and layered inorganic compounds such as vermiculite, montmorillonite, hectorite, hydrotalcite and synthetic mica. It is done. The average particle diameter of these inorganic particles is preferably 0.005 to 10 μm and more preferably 0.005 to 5 μm from the viewpoint of the stability of the aqueous dispersion. In addition, you may mix and use an inorganic particle according to each objective. For example, zinc oxide can be used for ultraviolet shielding, and tin oxide can be used for antistatic purposes.

Examples of pigments and dyes include titanium oxide, zinc white, and carbon black, and any of disperse dyes, acid dyes, cationic dyes, reactive dyes, and the like can be used.
If necessary, various agents such as a leveling agent, an antifoaming agent, an anti-waxing agent, a pigment dispersant, an ultraviolet absorber, a thickener, a weathering agent, a flame retardant are added to the aqueous dispersion of the present invention. It is also possible. These may be used alone or in combination of two or more.

<Method for producing aqueous dispersion>
The acid-modified polyolefin resin aqueous dispersion of the present invention is obtained by the following production method.
First, an acid-modified polyolefin resin solution is obtained by mixing with a water-soluble organic solvent having a boiling point of 100 ° C. or less so that the acid-modified polyolefin resin concentration is 1% by mass or less. Then, this solution is added to an aqueous medium having a mass 1.5 times or more that of this solution to obtain a mixed solution of the acid-modified polyolefin resin solution and the aqueous medium. Next, by volatilizing at least a part of the water-soluble organic solvent having a boiling point of 100 ° C. or lower in the obtained mixed liquid by a solvent removal treatment, an aqueous solution substantially free of a non-volatile aqueous dispersion aid and a basic compound is obtained. It is possible to produce a dispersion.

An acid-modified polyolefin resin solution containing an acid-modified polyolefin resin in 1% by mass or less of the entire solution in a water-soluble organic solvent having a boiling point of 100 ° C. or less will be described.
The water-soluble organic solvent having a boiling point of 100 ° C. or less preferably has a solubility in water at 20 ° C. of 50 g / L or more, more preferably 100 g / L or more, further preferably 200 g / L or more, and 500 g / L or more. Are particularly preferred, and those that dissolve in water in any amount are most preferred. If the solubility in water at 20 ° C. is less than 50 g / L, the dissolved acid-modified polyolefin resin may precipitate in the step of adding to an aqueous medium described later. The boiling point of the water-soluble organic solvent needs to be 100 ° C. or lower, preferably 90 ° C. or lower, more preferably 80 ° C. or lower, and particularly preferably 70 ° C. or lower. If the boiling point exceeds 100 ° C., it will be difficult to volatilize during the solvent removal treatment described below.

Furthermore, the water-soluble organic solvent having a boiling point of 100 ° C. or less preferably has high solubility of the acid-modified polyolefin resin, and more specifically, a solvent that can be dissolved at an acid-modified polyolefin resin concentration of 1% by mass or more is more preferable. More preferably, it is more preferably 3% by mass or more, and most preferably 5% by mass or more. If the concentration of the acid-modified polyolefin resin is less than 1% by mass, in the step of adding to the aqueous medium described later, if the concentration of the solution in which the acid-modified polyolefin resin is dissolved is not considerably reduced, precipitation may occur. Deteriorate.
Specific examples of the water-soluble organic solvent having a boiling point of 100 ° C. or lower include tetrahydrofuran, 1,2-dimethoxyethane, acetone, methyl ethyl ketone, acetonitrile and the like. Among them, tetrahydrofuran which is excellent in the suitability of this production method is preferable.

  In this production method, an acid-modified polyolefin resin solution containing an acid-modified polyolefin resin in an amount of 1% by mass or less of the entire solution is prepared in advance in a water-soluble organic solvent having a boiling point of 100 ° C. or less. The method for dissolving the acid-modified polyolefin resin is not particularly limited. When dissolving, stirring or heating may be used to increase the dissolution rate.

  In this production method, the acid-modified polyolefin resin concentration in the acid-modified polyolefin resin solution is a particularly important factor, and the concentration needs to be 1% by mass or less, and the upper limit of the concentration is 0.9% by mass or less. Preferably, 0.8 mass% or less is more preferable, 0.7 mass% or less is more preferable, 0.6 mass% or less is particularly preferable, and 0.5 mass% or less is most preferable. The lower limit of the concentration is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and further preferably 0.2% by mass or more from the viewpoint of productivity. When the acid-modified polyolefin resin concentration exceeds 1% by mass, the dissolved acid-modified polyolefin resin is precipitated in the step of adding to the aqueous medium described later, and an aqueous dispersion cannot be obtained.

In this production method, the acid-modified polyolefin resin having a boiling point of 100 is added by adding the acid-modified polyolefin resin solution having a concentration of 1% by mass or less to an aqueous medium having a mass 1.5 times or more of the solution. It can be uniformly dispersed in a mixture of a water-soluble organic solvent and an aqueous medium at a temperature of 0 ° C. or lower. The method for adding the acid-modified polyolefin resin solution to the aqueous medium is not particularly limited, but it is preferable to add the resin solution while stirring the aqueous medium.
Moreover, in this manufacturing method, although the method of adding an aqueous medium to an acid-modified polyolefin resin solution may be sufficient, the method of adding an acid-modified polyolefin resin solution to an aqueous medium is preferable. In the method of adding an aqueous medium to the acid-modified polyolefin resin solution, the acid-modified polyolefin resin may be precipitated in the mixed solution, and it may be difficult to disperse the acid-modified polyolefin resin.
In addition, the aqueous medium used by this method is the same as the said aqueous medium.

  The amount of the aqueous medium to which the acid-modified polyolefin resin solution is added is preferably 1.5 times or more of the total mass of the acid-modified polyolefin resin solution, and more preferably in the range of 1.7 to 10 times. Preferably, 2 to 8 times is more preferable, and 2.5 to 5 times is particularly preferable. When the mass of the aqueous medium is less than 1.5 times the entire acid-modified polyolefin resin solution, the acid-modified polyolefin resin may not be sufficiently dispersed. On the other hand, if it exceeds 10 times, the acid-modified polyolefin resin becomes too dilute and the productivity in the solvent removal treatment described later is inferior.

  When the acid-modified polyolefin resin solution is added to the aqueous medium, one or both of the acid-modified polyolefin resin solution and the aqueous medium may be cooled or heated, and the temperature is not particularly limited, but is 0 to 100 ° C. It is preferable from a viewpoint of workability to be in the range.

  When the acid-modified polyolefin resin solution is added to the aqueous medium, the addition rate (flow rate) is not particularly limited, and may be gradually added at a low flow rate or may be added at a high flow rate. Moreover, the place of addition is not particularly limited, and it may be in an airtight container or an open container. As described above, when the acid-modified polyolefin resin solution is added in the container, the aqueous medium is preferably stirred. On the other hand, the pipe through which the acid-modified polyolefin resin solution flows and the pipe through which the aqueous medium flow may be joined together while adjusting the flow rate in both pipes, and both may be mixed (add the solution to the aqueous medium) in the pipe. In this case, it is preferable that the pipe after joining has a structure that promotes the homogenization of both liquids, such as a static mixer.

  By the above-described method, the acid-modified polyolefin resin can be uniformly dispersed in a mixed solution of a water-soluble organic solvent having a boiling point of 100 ° C. or lower and an aqueous medium. The concentration of the modified polyolefin resin is very dilute, and further contains a large amount of organic solvent, and it is difficult to coat the coating film to a preferred thickness, or from the perspective of air pollution caused by the organic solvent, etc. There is a problem in practical use. Therefore, in this production method, it is preferable to volatilize at least a part of the water-soluble organic solvent having a boiling point of 100 ° C. or less in the mixed solution by a solvent removal treatment.

Hereinafter, the solvent removal process will be described.
Solvent removal treatment in this production method means volatilizing at least a part of a water-soluble organic solvent having a boiling point of 100 ° C. or less in a mixed solution of an acid-modified polyolefin resin solution and an aqueous medium, and determining the amount of the organic solvent in the mixed solution. It is a process to reduce. Thus, an acid-modified polyolefin resin aqueous dispersion can be obtained by reducing the amount of the organic solvent from the mixed solution. The method of solvent removal treatment is not particularly limited, and a known method can be adopted. Specifically, a method of heating and / or reducing the pressure of the mixed solution and distilling off the water-soluble organic solvent out of the system is preferably employed. The heating temperature is not particularly limited, but is preferably in the range of 40 to 200 ° C, more preferably 50 to 150 ° C, and still more preferably 60 to 120 ° C, from the viewpoints of volatilization efficiency and workability. The degree of reduced pressure is not particularly limited, but is preferably such that the mixed solution does not bump suddenly or vigorously boil, and may be appropriately adjusted within a range in which such a phenomenon does not occur. By such solvent removal treatment, all of the water-soluble organic solvent having a boiling point of 100 ° C. or less may be removed from the mixed solution, or a part thereof may be left in the aqueous dispersion from the viewpoint of improving paintability. .

  Further, in the solvent removal treatment, it is preferable to remove not only the water-soluble organic solvent having a boiling point of 100 ° C. or less, but also a part of water in the mixed solution from the mixed solution. Thus, by removing a part of water, it is possible to adjust the content of the acid-modified polyolefin resin in the aqueous dispersion to a preferable range.

  In addition, in the method for producing an aqueous dispersion of an acid-modified polyolefin resin of the present invention, when the acid-modified polyolefin resin solution is mixed by adding to an aqueous medium, the start time of the solvent removal treatment is the acid-modified polyolefin of the previous step. It may be started after the step of adding the resin solution to the aqueous medium is completed (that is, after the entire amount of the solution is added to the aqueous medium), or the acid-modified polyolefin resin solution of the previous step is added to the aqueous medium. You may start by heating or decompressing in the middle.

  By the above method, it is possible to obtain an aqueous dispersion in which the particles of the acid-modified polyolefin resin are uniformly dispersed in the aqueous medium with little or no undispersed resin remaining. However, a filtration step may be provided when the aqueous dispersion is dispensed from the apparatus in order to remove foreign substances in the container and a small amount of undispersed resin. Although the filtration method is not limited, For example, the method of carrying out pressure filtration (for example, air pressure 0.5MPa) with a 300 mesh stainless steel filter (wire diameter 0.035mm, plain weave) is mentioned. By providing such a filtration step, even if foreign matter or undispersed resin is present, they can be removed, so that the obtained aqueous dispersion can be used without any problem.

  The aqueous acid-modified polyolefin resin dispersion of the present invention obtained by such a method is excellent in adhesiveness to various substrates such as thermoplastic resins, metals, glass, paper, and synthetic paper.

Usable thermoplastic resins include nylon resins such as nylon 6, nylon 66, nylon 46, polyethylene terephthalate, polyethylene naphthalate, polytrimethylene terephthalate, polytrimethylene naphthalate, polybutylene terephthalate, polybutylene naphthalate, polylactic acid. Polyester resins such as polypropylene, polyethylene, and the like, polyimide resins, polyarylate resins, and mixtures thereof. Among these, polyamide resins, polyester resins, and polyolefin resins that are excellent in adhesion can be preferably used.
As a form of a thermoplastic resin, a molded object, a film, a nonwoven fabric, etc. are preferable, and a film is more preferably used especially. The film may be an unstretched film or a stretched film, and the production method is not limited. Although the thickness of a thermoplastic resin film is not specifically limited, Usually, what is necessary is just 1-500 micrometers.

  The aqueous acid-modified polyolefin resin dispersion of the present invention can be applied by a known coating method. As a coating method, various substrate surfaces can be formed by known film forming methods such as gravure roll coating, reverse roll coating, wire bar coating, lip coating, air knife coating, curtain flow coating, spray coating, dip coating, and brushing. It is possible to form a uniform resin coating in close contact with the surface of various substrates by coating it uniformly and setting it at around room temperature as necessary, followed by heat treatment for drying or drying and baking. it can. As a heating device at this time, a normal hot air circulation type oven, an infrared heater, or the like may be used.

  The thickness of the resin coating film formed using the acid-modified polyolefin resin aqueous dispersion of the present invention is appropriately selected depending on the application, but is preferably 0.01 to 30 μm, preferably 0.02 10 to 10 μm is more preferable, 0.03 to 9 μm is further preferable, and 0.05 to 8 μm is particularly preferable. When the thickness of the resin coating film is less than 0.01 μm, the heat sealability deteriorates. In addition, since the resin coating film formed using the acid-modified polyolefin resin aqueous dispersion of the present invention exhibits various excellent performances including heat sealability with a thickness of several μm or less, there is no particular reason. For example, it is not necessary to coat the aqueous dispersion beyond 10 μm. In order to adjust the thickness of the resin coating film, an apparatus used for coating and its use conditions are appropriately selected, or an acid-modified polyolefin resin aqueous dispersion having an appropriate concentration is used.

  The use of the acid-modified polyolefin resin aqueous dispersion of the present invention is not particularly limited, and includes a surface modifier, an anchor coat agent for extrusion lamination, a release layer of a release film, a heat seal agent, an adhesive, a binder, and the like. It is possible to use it suitably.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.
Various characteristics were measured or evaluated by the following methods.

1. Characteristics of acid-modified polyolefin resin (1) Content of unsaturated carboxylic acid unit The acid value of the acid-modified polyolefin resin is measured according to JIS K5407, the mass of unsaturated carboxylic acid is calculated from the value, and the content is expressed by the following formula: I asked for it.
Content (mass%) = (mass of unsaturated carboxylic acid) / (mass of acid-modified polyolefin resin) × 100

(2) Constitution of Resin Other than Unsaturated Carboxylic Acid Unit ¹ H-NMR and ¹³ C-NMR analysis (manufactured by Varian, 300 MHz) was performed at 120 ° C. in orthodichlorobenzene (d ₄ ). ^{In 13} C-NMR analysis, measurement was performed based on a gated decoupling method in consideration of quantitativeness.

(3) Melt flow rate value It calculated | required by 190 degreeC and the 21.2N load according to ISO1133.

2. Characteristics of Aqueous Dispersion (1) Volume average particle diameter of resin particles Volume average particle diameter was measured using a Microtrac particle size distribution analyzer UPA150 (MODEL No. 9340) manufactured by Nikkiso Co., Ltd. The refractive index of the resin was 1.5.

(2) pH
The pH was measured using a pH meter (Horiba, Ltd., F-52).

(3) Adhesion (tape peeling test)
Biaxially stretched polyethylene terephthalate film (thickness 25 μ, no corona treatment, hereinafter referred to as “PET”), unstretched polypropylene film (thickness 50 μ, no corona treatment, hereinafter denoted as “CPP”), unstretched polyethylene film (thickness 50 μ, No corona treatment, hereinafter referred to as “PE”) or biaxially stretched nylon 6 film (thickness 15 μ, no corona treatment, hereinafter referred to as “Ny6”) so that the coating thickness after drying the aqueous dispersion is 10 μm After coating with a Meyer bar, it was dried at 90 ° C. for 2 minutes. After leaving this at room temperature for 1 day, a cellophane tape (TF-12 manufactured by Nichiban Co., Ltd.) was applied to the coating film, and the degree of peeling when the tape was peeled at once was visually evaluated according to the following criteria.
○: No peeling at all △: Some peeling off ×: Most peeling off

(4) Water resistance The aqueous dispersion was coated on CPP using a Meyer bar so that the thickness of the coating film after drying was 10 μm, and then dried at 90 ° C. for 2 minutes. This was allowed to stand at room temperature for 1 day, then immersed in water at 50 ° C. for 7 days, and the state of the coating film was visually evaluated according to the following criteria.
○: No change from before immersion △: Whitening ×: There was peeling

  The following P-1 to P-6 were used as polyolefin resins used in Examples and Comparative Examples.

P-1:
100 g of ethylene-butene copolymer (ethylene / 1-butene = 70/30% by mass) was dissolved in 400 g of xylene heated to 100 ° C. in a four-necked flask under a nitrogen atmosphere. Next, 10 g of a toluene solution of maleic anhydride (maleic anhydride content 5 mass%) and 5 g of a dicumyl peroxide toluene solution (dicumyl peroxide content 10 mass%) were respectively added to this solution over 30 minutes. Thereafter, the system was kept at 130 ° C. for 4 hours. After completion of the reaction, the obtained reaction product was put into a large amount of acetone to precipitate a resin. This resin was further washed several times with acetone and dried under reduced pressure, and the resulting acid-modified polyolefin resin P-1 was used.

P-2:
In the production of P-1, except that the ethylene-butene copolymer (ethylene / 1-butene = 70/30% by mass) was changed to an ethylene-propylene copolymer (ethylene / propylene = 75/25% by mass), The same operation was performed and the obtained acid-modified polyolefin resin P-2 was used.

P-3
In the production of P-1, the same operation was carried out except that the amount of maleic anhydride in toluene was changed from 10 g to 1.5 g, and the resulting acid-modified polyolefin resin P-3 was used.

P-4
In the production of P-1, the same procedure was performed except that the amount of maleic anhydride in toluene was changed from 10 g to 70 g, the amount of dicumyl peroxide in toluene was changed from 5 g to 20 g, and the system temperature was changed from 130 ° C to 140 ° C. The obtained acid-modified polyolefin resin P-4 was used after operation.

P-5
In the production of P-1, the same procedure was performed except that the amount of maleic anhydride in toluene was changed from 10 g to 150 g, the amount of dicumyl peroxide in toluene was changed from 5 g to 50 g, and the internal temperature was changed from 130 ° C to 140 ° C. The operation was performed and the resulting acid-modified polyolefin resin P-5 was used.

P-6
Bondaine “LX-4110” (ethylene / ethyl acrylate / maleic anhydride copolymer) manufactured by Arkema Co., Ltd., which is a commercial product, was used.

P-7
An acid-modified ethylene-butene copolymer (ethylene / 1-butene = 70/30% by mass) was used.

  Table 1 shows the characteristics of the polyolefin resins P-1 to P-7.

Example 1
P-1 was used as the acid-modified polyolefin resin, and tetrahydrofuran (boiling point 66 ° C., hereinafter referred to as “THF”) was used as the water-soluble organic solvent having a boiling point of 100 ° C. or less. A P-1 solution having a P-1 content of 0.5 mass% was prepared by mixing, heating, and stirring 25 g of P-1 and 4,975 g of THF.
Next, 10,000 g (twice the mass of the P-1 solution) ion-exchanged water as an aqueous medium was charged into a container equipped with a stirrer and a heater, and 5,000 g of the P- was stirred while stirring with the stirrer. 1 solution was gradually added over 5 minutes, and the liquid mixture which consists of ion-exchange water and P-1 solution was produced. In this mixed solution, the acid-modified polyolefin resin was uniformly dispersed (uniformly cloudy).
The obtained mixed liquid was heated to 60 ° C. with a heater, and the inside of the container was gradually decompressed while stirring. The vapors of THF and water generated by heating and decompression were condensed outside the container and distilled out of the container. When the mass of the aqueous dispersion in the container became 200 g or less, the aqueous dispersion was filtered under pressure with a 300-mesh stainless steel filter (wire diameter 0.035 mm, plain weave). At this time, there was no undispersed material on the filter after filtration. Ion exchange water was added to the aqueous dispersion after filtration to adjust the content of the acid-modified polyolefin resin to 10% by mass. In this way, an aqueous dispersion of P-1 was obtained (uniformly cloudy).

Examples 2-6
As an acid-modified polyolefin resin, instead of P-1, P-2 (Example 2), P-3 (Example 3), P-4 (Example 4), P-5 (Example 5) or P- Except that 6 (Example 6) was used, an aqueous dispersion of P-2 to P-6 having an acid-modified polyolefin resin content of 10% by mass was finally obtained in the same manner as in Example 1. In the mixed liquids obtained in Examples 2 to 6, the acid-modified polyolefin resin was uniformly dispersed (uniformly clouded). In Examples 2, 4, 5, and 6, no undispersed resin was present on the filter after filtration. In Example 3, after filtration, an undispersed resin was confirmed on the filter, and the entire amount of the undispersed material was recovered and the dry mass was measured to be about 1 g.

Example 7
By mixing, heating and stirring 50 g of P-1 and 4,950 g of THF, a P-1 solution having a P-1 content of 1% by mass was produced. A P-1 aqueous dispersion having an acid-modified polyolefin resin content of 10% by mass was finally obtained in the same manner as in Example 1 except that the P-1 solution concentration used was changed to a 1% by mass solution. . In the mixed liquid, the acid-modified polyolefin resin was dispersed (white turbidity), but a small amount of precipitate was partially confirmed. Further, after filtration, an undispersed resin was confirmed on the filter, and the entire amount of the undispersed material was recovered and the dry mass was measured to be about 2 g.

Example 8
Finally, in the same manner as in Example 1, except that 7,500 g (1.5 times the mass of P-1 solution) of ion-exchanged water was used instead of 10,000 g of ion-exchanged water as the aqueous medium. An aqueous dispersion of P-1 having an acid-modified polyolefin resin content of 10% by mass was obtained. In the mixed liquid, the acid-modified polyolefin resin was dispersed (white turbidity), but a small amount of precipitates composed of the acid-modified polyolefin resin was confirmed. Further, after filtration, an undispersed resin was confirmed on the filter, and the entire amount of the undispersed material was recovered and the dry mass was measured to be about 2 g.

Comparative Example 1
Using P-7 as an acid-modified polyolefin resin, 25 g of P-7 and 4,975 g of THF were mixed, heated, and stirred to obtain a P-7 solution having a P-7 content of 0.5 mass%. Produced.
Next, 10,000 g (twice the mass of the P-7 solution) ion-exchanged water as an aqueous medium was charged into a container equipped with a stirrer and a heater, and 5,000 g of the P-7 was stirred with the stirrer. The solution was gradually added over 5 minutes to prepare a mixed solution composed of ion-exchanged water and P-1 solution. In this mixed solution, the acid-modified polyolefin resin was not dispersed at all, and a large amount of precipitates composed of the acid-modified polyolefin resin was confirmed. Therefore, an aqueous dispersion was not obtained.

Comparative Example 2
A pressure vessel equipped with a heater and a stirrer was charged with 100 g of P-1, 250 g of THF, 20 g of dimethylaminoethanol (basic compound) and 630 g of ion-exchanged water, and after sealing, heated with stirring at 200 rpm. Hold at 130 ° C. for 2 hours. At this time, the acid-modified polyolefin resin was not dispersed at all. Therefore, an aqueous dispersion was not obtained.

Comparative Example 3
A pressure vessel equipped with a heater and a stirrer was charged with 100 g of P-5, 250 g of THF, 20 g of dimethylaminoethanol (basic compound), and 630 g of ion-exchanged water, and after sealing, heated with stirring at 200 rpm. Hold at 130 ° C. for 2 hours. At this time, in the aqueous dispersion, the acid-modified polyolefin resin was uniformly dispersed (uniformly cloudy). When the output of the heater was set to zero and the internal temperature decreased to 80 ° C. by natural cooling, the inside of the container was decompressed and reheated. The generated vapor was condensed outside the container and distilled out of the container. When the mass of the aqueous dispersion in the container is 600 g or less, the outputs of the heater and the stirrer are made zero, and then the aqueous dispersion is pressure filtered through a 300 mesh stainless steel filter (wire diameter 0.035 mm, plain weave). did. At this time, there was no undispersed material on the filter after filtration. Ion exchange water was added to the aqueous dispersion after filtration to adjust the content of the acid-modified polyolefin resin to 10% by mass. In this manner, an aqueous dispersion of P-5 containing a basic compound was obtained.
In addition, when acetic acid was added to adjust the aqueous dispersion to be acidic, precipitation of acid-modified polyolefin resin dispersed particles was generated, and the dispersion dispersion was not acidic.

Reference example 1
P-1 was used as the acid-modified polyolefin resin, and N, N-dimethylformamide (boiling point 153 ° C., hereinafter referred to as “DMF”) was used as the water-soluble organic solvent. By mixing, heating, and stirring 25 g of P-1 and 4,975 g of DMF, a P-1 solution having a P-1 content of 0.5 mass% was prepared.
Next, 10,000 g (twice the mass of the P-1 solution) ion-exchanged water as an aqueous medium was charged into a container equipped with a stirrer and a heater, and 5,000 g of the P-1 was stirred with the stirrer. The solution was gradually added over 5 minutes to prepare a mixed solution composed of ion-exchanged water and P-1 solution. In this mixed solution, the acid-modified polyolefin resin was uniformly dispersed (uniformly cloudy).
Further, as a solvent removal treatment, the obtained mixed solution was heated to 60 ° C. with a heater, and the inside of the container was gradually decompressed while stirring. DMF and water vapor generated by heating and decompression was condensed outside the container and distilled out of the container. When this solvent-removing treatment was continued, the cloudiness gradually disappeared and the liquid became a transparent liquid, and an aqueous dispersion could not be obtained.

Reference example 2
P-1 was used as the acid-modified polyolefin resin, and 1,2-dichloroethane (boiling point: 84 ° C., hereinafter referred to as “DCE”), which is water-insoluble, was used as the organic solvent. By mixing, heating, and stirring 25 g of P-1 and 4,975 g of DCE, a P-1 solution having a P-1 content of 0.5 mass% was prepared.
Next, 10,000 g (twice the mass of the P-1 solution) ion-exchanged water as an aqueous medium was charged into a container equipped with a stirrer and a heater, and 5,000 g of the P-1 was stirred with the stirrer. The solution was gradually added over 5 minutes to prepare a mixed solution composed of ion-exchanged water and P-1 solution. In this mixed solution, the acid-modified polyolefin resin was not dispersed at all, and a large amount of precipitates composed of the acid-modified polyolefin resin was confirmed. Therefore, an aqueous dispersion was not obtained.

Reference example 3
A P-1 solution having a P-1 content of 1.3% by mass was prepared by mixing, heating, and stirring 65 g of P-1 and 4,935 g of THF.
Next, 10,000 g (twice the mass of the P-1 solution) ion-exchanged water as an aqueous medium was charged into a container equipped with a stirrer and a heater, and 5,000 g of the P-1 was stirred with the stirrer. The solution was gradually added over 5 minutes to prepare a mixed solution composed of ion-exchanged water and P-1 solution. In this mixed solution, the acid-modified polyolefin resin was not dispersed at all, and a large amount of precipitates composed of the acid-modified polyolefin resin was confirmed. Therefore, an aqueous dispersion was not obtained.

Reference example 4
A P-1 solution having a P-1 content of 0.5 mass% was prepared by mixing, heating, and stirring 25 g of P-1 and 4,975 g of THF.
Next, 6,500 g (1.3 times mass of P-1 solution) ion-exchanged water as an aqueous medium was charged into a container equipped with a stirrer and a heater, and 5,000 g of the P was stirred while stirring with the stirrer. -1 solution was gradually added over 5 minutes, and the liquid mixture which consists of ion-exchange water and P-1 solution was produced. In this mixed solution, the acid-modified polyolefin resin was uniformly dispersed (uniformly clouded), but the degree of white turbidity was thinner than that of the mixed solution of Example 1.
Further, as a solvent removal treatment, the obtained mixed solution was heated to 60 ° C. with a heater, and the inside of the container was gradually decompressed while stirring. The vapors of THF and water generated by heating and decompression were condensed outside the container and distilled out of the container. When this solvent removal treatment was continued, the acid-modified polyolefin resin gradually precipitated and finally almost all of the acid-modified polyolefin resin precipitated, and an aqueous dispersion could not be obtained.

Reference Example 5
Instead of 10,000 g of ion exchange water as an aqueous medium, 10,000 g of sodium hydroxide aqueous solution having a sodium hydroxide content of 0.0025% by mass (sodium hydroxide / ion exchange water = 0.25 g / 9,999.999). An aqueous dispersion of P-1 was obtained in the same manner as in Example 1 except that 75 g) was used. In the mixed solution before obtaining the aqueous dispersion, the acid-modified polyolefin resin was uniformly dispersed (uniformly clouded). Also, after filtration, there was no undispersed resin on the filter.

  Table 2 shows the characteristics of the aqueous dispersions obtained in Examples 1 to 8, Comparative Examples 1 to 3, and Reference Examples 1 to 5.

  In Examples 1 to 8, aqueous dispersions containing no non-volatile aqueous dispersion aid and basic compound were obtained. The obtained aqueous dispersion was excellent in adhesion to various substrates. Moreover, since it does not have a basic compound such as an amine, the safety is high and there is no malodor originating from the amine. Furthermore, the aqueous dispersion had dispersion stability even when the pH was acidic.

  In Example 3, since the unsaturated carboxylic acid content of the acid-modified polyolefin resin used was 0.01% by mass and the lower limit of the preferred unsaturated carboxylic acid content of the present invention, the acid-modified polyolefin resin was modified during the production. A part of the polyolefin resin was precipitated and there was some loss. On the other hand, in Examples 5 and 6, since the unsaturated carboxylic acid content exceeded the preferred range, the water resistance tended to be slightly lower than in the other examples.

  Moreover, in Example 7, since the P-1 content of the P-1 solution used was 1% by mass and the upper limit of the preferred content of the present invention during production, a part of the acid-modified polyolefin resin was precipitated. There was some loss. In Example 8, since the amount of the aqueous medium used in the production was 1.5 times the mass of the acid-modified polyolefin resin solution and the lower limit of the preferred amount of the present invention, a part of the acid-modified polyolefin resin was precipitated. There was some loss.

  In Comparative Example 1, an aqueous dispersion was not obtained because the polyolefin resin used did not have an unsaturated carboxylic acid.

  In Comparative Example 2, aqueous dispersion was attempted by a conventionally known production method using a basic compound, but the content of unsaturated carboxylic acid in the acid-modified polyolefin resin solution was as low as 0.21% by mass. No body was obtained.

  In Comparative Example 3, a known aqueous dispersion was obtained in which an acid-modified polyolefin resin having an unsaturated carboxylic acid content of 4.81% by mass was produced by a conventionally known production method using a basic compound. Although this aqueous dispersion was excellent in adhesion, it contained an amine, which is a basic compound, and there was a concern that safety and odor problems would occur. In addition, this aqueous dispersion does not have acid stability, is only alkaline and stable, and its intended use is limited.

  In Reference Example 1, since the water-soluble organic solvent used in the production was N, N-dimethylformamide that deviated from the preferred boiling point of the present invention, in Reference Example 2, the solvent used in the production was water-insoluble. 1,2-dichloroethane was used, and in Reference Example 3, the P-1 solution used in the production had a P-1 content of 1.3% by mass and deviated from the preferred content of the present invention. In Reference Example 4, since the amount of the aqueous medium used in the production was 1.3 times the mass of the acid-modified polyolefin solution, which was out of the preferred amount of the present invention, an aqueous dispersion could not be obtained.

In Reference Example 5, sodium hydroxide was intentionally added during the production of the aqueous dispersion in order to adjust the pH of the obtained aqueous dispersion to be alkaline. The body had dispersion stability even if it was alkaline. Further, there was no decrease in adhesion and water resistance performance with respect to Example 1. Thus, it was confirmed that the aqueous dispersion of the present invention has dispersion stability even when alkalinity is required for the intended use, and can be used for a wide range of uses.

Claims (6)

An aqueous acid-modified polyolefin resin dispersion comprising an acid-modified polyolefin resin and an aqueous medium, and substantially free of a non-volatile aqueous dispersion aid and a basic compound. The acid-modified polyolefin resin aqueous dispersion according to claim 1, wherein the pH is 4.0 to 11.0. The acid-modified polyolefin resin aqueous dispersion according to claim 1 or 2, wherein the content of the unsaturated carboxylic acid in the acid-modified polyolefin resin is 0.01 to 1% by mass. The acid-modified polyolefin resin aqueous dispersion according to any one of claims 1 to 3, wherein the acid-modified polyolefin resin is an acid-modified ethylene / α-olefin copolymer. The mass ratio (ethylene / α-olefin) of ethylene and α-olefin constituting the acid-modified ethylene / α-olefin copolymer is 60/40 to 99/1. Any one of the acid-modified polyolefin resin aqueous dispersions. In a water-soluble organic solvent having a boiling point of 100 ° C. or less, an acid-modified polyolefin resin solution containing 1% by mass or less of the acid-modified polyolefin resin is added to an aqueous medium having a mass 1.5 times or more of the solution. Then, at least a part of the water-soluble organic solvent having a boiling point of 100 ° C. or less in the obtained mixed liquid is volatilized by a solvent removal process, and a method for producing an aqueous dispersion of an acid-modified polyolefin resin.